Electromagnetic apparatus



July 2, 1946c FIGI.

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M; P. WINTHER ELECTROMAGNETIC APPARATUS Filed March 12. 1945 6sheets-sheet 1 ML K )x July 2, 1946. M. WINTHER 2,403,4214

ELECTROMAGNETIC APPARATUS Fled'March 12, 1945 6 Sheets-Sheet 2 July 2,1946.

M. P. WINTHER ELECTROMAGNETIG APPARATUS Filed March 12, 1945 6Sheets-Sheet 3 July 2, 1946. M. P. wlNTHER ELECTROMAGNETIC APPARATUSFiled March l2, 1945 6 Sheets-Sheet 4 July 2, 1946. l M. P. WIN'THER2,403,421

ELECTROMAGNETIC APPARATUS July z, 1946.

A M. P. WINTHER ELECTROMAGNETIG APPARATUS n 6 Sheets-Sheet 6 Filed March12, 1945 NOE Patented July 2, 1946 ELECTROMAGNETIC APPARATUS Martin P.Winther, Waukegan, nl., assigner to Martin P. Winther, as trusteeApplication March 12, 1945, Serial No. 582,301-

(Cl. 18S-104) 1 18 Claims. This invention relates to electromagneticapparatus, and with regard'to certain more speciiic features, tohigh-speed, high-capacity dynamoineters and the like.

Among the several objects of the invention may be noted the provision ofa water-cooled, eddy-current. dynamometer adapted to operate safely athigh speeds and to absorb heavy loads; the provision of a dynamometerofthe class described which will pass large volumes of cooling water forhigh rates of energy absorption without introducing parasitic unsteadytorque; the provision .of a machine of the class described which employsa rotor and a method of cooling it adapted to minimize distortions underhigh rotor speeds; and the provision of a machine of this class which issimple and economical to build and maintain. Other objects will be inpart obvious and in part pointed out hereinafter.

'I'he invention accordingly comprises thev elements and combinations ofelements, features of construction, and arrangements of parts which willbe exemplied in the structures hereinafter described, and the scope ofthe application of which will be indicated in the following claims.

In the accompanying drawings, in which is illustrated one of variouspossible embodiments of the invention,

Fig. 1 is an end view of one component dy narnometer unit embodyingfeatures of the invention;

Fig. 2 is a left-side view of Fig. 1;

Fig. 3 is a partial longitudinal section of one unit on a slightlyenlarged scale with respect to that of Fig. 1;

Fig. 4 is a vertical section taken online 4-4 of Fig. 3i I Fig. 5 is ahorizontal section taken on line 5-.-5 of Fig. 1 but on a furtherenlarged scale;

Fig. 6 is a diagrammatic plan view of several combined units embodyingother features of the invention; and I Fig. 7 is a detail section takenon line of Fig. 6.

Similar reference characters indicate corresponding parts throughoutthe-several views of the drawings.

Increasing sizes of engines to be tested at high speeds are presentingincreasing problems in the dynamometer test. ileld. By means of theapparatus herein described 15,000 H. P. may be absorbed at from 8,000 to12,000 R. P. M. This is done with relatively simple and safe apparatusrequiring a. minimum in control organization.

, 59 having flexible exterior connections lead oil Referring nowmoreparticularly to Fig. l, there is shown at numeral I a platform, uponwhich are mounted pedestals 3 and 5 (Fig. 2). The pedestals 3incorporate bearing structures which are not new herein but which aredescribed for completeness. Each of thes'e bearings (note the one ofFig. 3 for example) consists' in enclosing members 1 and 9 wherein aresupporting bearing rings II and I3 for supporting outer bearing flangesI5 of a ring gear I1, the rim of the latter extending radially betweenthe bearing rings II and I3 (see also Fig. 5). An inner hub I9 of thering gear containsthe outer race 2| of a roller bearing 23. Theinnerrace 25 of this bearing 23 is carried on a neck l21 of a rockingstator S, to be described hereunder in detail.

As indicated in Fig. 5, the teeth 29 of the gear I1 mesh with a pinion3l on a countershaft 35 supported in outboard bearings 33. Thecountershaft 35 carries a sprocket 31 connected by a chain 39 with asprocket 4I on the shaft 43 of a worm-gear speed reducer 45. The speedAreducer 45 is continuously driven from a motor 41. The

' purpose of this type of bearing for each neck 21 is to maintain acontinuous slow rolling of the bearings 23 so that each does notcontinuously load one spot on the races 2| and 25, as would besubstantially the case if these bearings did not continuously progress-`It will be appreciated from what follows that each neck 21, althoughit'rocks slightly, is essentially stationary during operation, theanti-friction bearing being basically necessary for the purpose ofpreventing loss of torque applied through the stator S to a suitabledynamometer measuring scale.

The stator S will now be described. It consists of opposite heads 49 and5I. Since the interior construction of the head 49 also exemplifies theinterior construction of the head 5I, only the former will be describedin detail so far as interior parts are concerned. Referring to Fig. 3,it will be seen that the neck 21 is on a bell 28 bolted to the head 49.In addition there is bolted to the inside of the head 49 a sleevebearing 53 which supports a gudgeon of a rotor R, also to be described.A labyrinth assembly 51 is carried on the inside of the head 49 and hasannular labyrinth dams 58 engaging portions toward the rotor R of thegudgeons 55. One or more oil leads to the bearings 53y and an overflowof pipe 92 carries off excess oil and' foreign material. A flexiblyconnected air port 8| serves to apply pressure to resist incipientlleakage into the labyrinth packing l1, the outlet for this air beingshown at 04.

The outer periphery of each head such as 4I is bolted as indicated at 83to an outer cylinder Il. Within endwise rings B1 this cylinder carriesan inner magnetic cylinder 80 made up of a series of rings 33 and 10.These rings are Joined by .pocket-forming rings 1| and 13 also composedof magnetic material. They are also joined by means of preferablynonmagnetic rings 1l.` although the latter may be magnetic. since theiiux leakage lost through them is ordinarily negligible. Members Il, I1,00,1I, 13 and 1l are suitably welded to form a double-walled hollowcylindrical rotor unit having the heads 40 and necks 21.

Within each annular recess formed by the rings 1| and 13 is aperipheralLv wound neld coil 11. One coil is shown in Fig. 3 but it willbe understood that toward the opposite end of the machine is anothersimilar coil symmetrically located with respect to a central plane.

Welded to the top arcuate portionsy (but not the bottom) of the rings 80and 10 are longi' tudinal magnetic teeth 8| and 83. These extendradially (Fig. 4). As indicated at 35, their ends extend under the coils11. 'I'hese teeth are widely spaced and their ends are tapered downpreferably to provide for approximate ilux saturation from their ends.The toric flux neld generated by one of the coils 11 is indicated inFig. 3 by dotted lines. It engenders. for example, a series of northpoles in the teeth Il within ring 03 and a series of opposite southpoles in teeth 33. If desired this polarity may be reversed by changingthe 'direction of current through the coils 11. This iiux traverses'thedrum I1 which forms the main part of the rotor R. Thus if the rotor,which is also magnetic, is caused to rotate. eddy currents areengendered therein. and the resulting reactive nux neld applies torqueto the stator S through the teeth and I0. This torque is in a proportionto the energy transformation accomplished by the heating of the cylinder01 by the eddy currents.

The cylinder 01 is solid and preferably made of generator steel. It hasa solidv stepped connection 30 with the gudgeon il. The gudgeon Il alsohas a solid connection withthe shaft 0| which extends from the machinefor attachment of an engine to be tested or for attachment to anotherdynamometer unit as will be described. The stepped connection 30cooperates with a stepped labyrinth 33 formed on the inside of anendwise water ring Il. The cooperating steps 00 and 03 act as anadditional liquid dam. v

A header ring 0B is attached at each end of the inner cylinder 0l formedby the rings Il and 1l. the outer cylinder 05 overlapping 0I endwise.Each ring 0l includes at the top a pair of water inlets 31 havingilexible connectors Il reaching to the opposite end of the machine.These sets of nexible connectors l! have connections III with watermanifolds |03. The manifold at the end of the machine corresponding tothe pedestal 3 is carried on the enclosures 4 p bility. The reason formaking the water connections 0B inv multiple, is that such connectionshave less resistance against bending than a single one of the samecapacity. Thus another source of parasitic torque on the stator isminimized. The connections 91 pass through the outer cylinder 0l throughopenings |01. Each water ring 0l is provided with a lower drain pipe asindicated at |00.

The outer casing BB isprovided in its bottom with relatively largeopenings through which extend drain pipes .i I3. Pipes I3 are incommunication with openings Il! in the bottom of the inner cylindercomposed by the rings 00 and 13.

The means for carrying water from the end liquid manifold rings 00 tothe outlets H5 is as follows, referring to Figs. 3 and 4. At intervalsalong the bottom of the rings 80 and 10 are supporting cross bridgeplates ill. Each clears the bottoms by means of an opening H0. Each ineffect forms an arch or bridge for accommodating free liquid ow beneathit. Each is perforated to carry axially disposed water tubes |2 Eachtube |2l is axially slotted as at |213 adiacent to the rotor cylinder l1so as to project a sheet of water against that cylinder. `Notches whichhold tubes |2| in the plates ||1 allow the issuing sheet to becontinuous throughout the length of the cylinder I1'.

Axially disposed deilectors' |25 are used above the lower nest of tubesI2| thus formed. A defiector |21 is also used between groups of five ofthese pipes and located at the bottom of the bridge plates li'l.I Thesedeilectors |25and |21 serve also as stiffening members between thebridged supports Il'l. From Fig. 4 it will be noted that the bridgesupports ||1 are welded to the inside of the rings 88 and 10.

A. single additional pipe |20 is used axially between the two uppermostgroups of teeth 0| and 83, the same being fastened to these by means ofwelded web plates |3|. This pipe, like the pipes I2I, is axially slottedadjacent the cylinder 01 to project liquid thereon. It is preferablethat all of the pipes I2| and |20 be nonmagnetic.` such as of brass. sothat they do not act as short circuits for the flux field issuing fromthe teeth Il.

All of the pipes I2I and |28 at'opposite ends of the machine arefastened into header rings |33 which form suitable inlets for the pipesfrom the ring manifolds 9B.

From the above it is evident that if water under suitable pressure(which may be low) is introduced into the end rings 8l it will progressto the pipes |2l and |29 and issue in radially directed, longitudinalsheets against the rotor 1, l. The manifold |03 carried at the other endAVfolds |03 is so that the flexible connections 33 may be as long aspossible for maximum flexicylinder I1. It will be noted however that byfar the greatest volume of water issues from the ten pipes at the bottomof the machine against the under side of the cylinder I1 and that only asmall amount, one-tenth (for example) by comparison, issues from theother pipe |29 against the upper side of the cylinder. This is animportant feature of the invention, taken in connection with the use ofa'limited number only of flux-concentrating teeth 0| over the upper arcof said cylinder 01 and in connection with free drainage facilities. Thespace below and between the rotor R and stator S is of'suiiicient volumeto accommodate a pool of coolant without the rotor dipping therein.

The cylinder 01 is heated strongly under the teeth 3|, due to the heavyeddy currents engendered therein. The heated surface then quickly sweepsdown into a voluminous flood of coolant (water for example) opposite thelower pipes |2I. This large flood of coolant may safely be appliedbecause in this region there are no heating in the cylinder 81 under theteeth 8|. Y

The defiectors |25 and |21 tend to baille the streams of water below thecylinder 81 and to prevent them from progressing upward.

Water is carried off from the outlets ||5 to the pipes I I3 into ahollow base |35 of which the platform I is the top. Relatively largeopenings I31 are applied in the top I movably to accommodate the pipes|I3, and the latter are connected to the top I by fiexble connectors |39so as to prevent vapor and thevlike from issuing from the base |35. Inthe base |35 is a suitable coolant sump I4I from which the received hotwater is pumped to cooling apparatus, or if desired for recirculation ormay be thrown away to waste. The base also contains whatever auxiliariesmay be required, such as an oil pressure lubricating system etc.

It will be seen from the above that the cylinder -81, the stepped downportion 89, gudgeon 55 and shaft 9| are all made integral and solid.This also favors high rotative speeds in addition to the diameter of thecylinder 81 being kept down las much as possible 4while relying uponlength increase for increased capacity.

' It will be noted also that the stator S is built up by welding fromvarious Cylinders, rings and the-like. This provides a substantialamount of empty space between rings 59, 10, 13 and the outer cylinder65, Hence a rigid doublebarreled stator structure is obtainedaccommodating the coil 11 and an ample flux path without increasing theweight of the stator unduly. By this means undue flux wandering is alsoprevented since it is confined entirely to the inner barrel 59, 1|, 13,10. In this respect it is important that the ring 13 be separated fromthe outer cylinder 65 by means of an air gap so that there will not be aloss of fiux from the flux circuits to outer cylinder 65. y

The rings 58 and 1|| joined by the rings 1| and 15 form an innerwaterproof structure joined to the outer cylinderv 65 by means of thespacing rings 31. 'I'his construction provides good rigidity withoutcommensurate increase of weight in` the stator. It also providesrecessed spaces for the coils 11 which needuto be located behind theteeth.8|, 83. The hollow heads 49 with the contained but separateheaders 95 favor a light construction without sacrice of strength.

Each unit (one ofwhich has been above described) is arranged'to becoupled in co-axial tandem with another so thatv a line of units may beused together, as shown by Fig. 6. Fig. 6 shows, for example, two unitscoupled together (one fragmentary). but it will be understood thatthree, four or more may be coupled for unitary action in tandem. Thecapacity above quoted, namely, 15,000 H.- P. absorptive capacity is forof the weight I5| of course willbe known, 'and 6 four units of the typeabove described coupled in tandem. This tandem coupling allows for alarge increase in speed because capacity is increased without undueincrease'in diameter of the cylinders 81. With smaller cylinders such as81 higher speeds are better tolerated.

The exterior of the apparatus will now be described in connection withFigs. 2, 6,1 and 7. vEach outer case or stator S is provided withopposite pads |42 for attachment on one or the other side of a suitablearm for yreaching to weighing apparatus for measuring force at a knownradius for calculating torque. Opposite threaded sockets |43 are alsoemployed for application in one of said sockets of a suitable arm(extending in the opposite direction from the arm in pad |42) to supporta dead weight. In

Fig. 6 an arm on a pad |42 is diagrammatically On the opposite side isshown in dotted lines y an arm |49 threaded into a socket |43 andsupporting a dead weight I5|. By this means the amount of weighing thatneeds to be done by means of the scale |41 in order to measure a giventorque is reduced by the amount of torque supplied by the dead weightI5|. The amount its moment plus that applied by the scale |41, will givethe total moment applied to the case. In Fig. 2, is shown a cover |53which is located over an inspection opening.

Coupling means are used between successive units in tandem as shown inFigs. 6 and '1. Coupling is accomplished by providing at each end of agiven unit two pairs of pads |55 (see also Fig. 2) for receivingextension trusses. The trusses on each side between adjacent units areindicated at 9| are connectedby couplings 92, as shown be- |51 and |59in Fig. 6. All of the trusses |51 and |59 are of general triangularshape, each having feet |6| for application to one of the pair of pads|55. Each |51 ends in a tongue |63. Each truss |59 ends in a clevis |65.When bolted into posiw 4tion the tongues |63 lie withinthe mouths of theclevises |65. Adjusting bolts |61 in opDO- site sides of the clevises|65 serve properly to eliminate lost angular motion. The rotor shaftstween the units in Fig. 6.

It will beobserved that if desired, added dead lweights such as I5| maybe applied to each of v the units in the series. More arms such as |45and scale |41 may also be used. But it is usually preferable to use onearm and one scale on a more or less central one of the umts and also toapply a single arm |49 and single dead weight |5I to said more or lesscentral unit. Through the truss couplings all of the torque from al1units may be weighed from one.

The break line in Fig. 6 indicates that more units may be inferred to bein the line of two shown therein.

The endmost unit, which is shown at the right in Fig. 6, may have itsshaft provided with a splined slidable crown coupling |59-for engagementand disengagement with a cooperating` amounts of energy and foraccurately measuring the resulting torque for computing horsepower.'I'he system employed lends itself to indennita increase in capacitywithout increasing rotor sizes by multiplying the -units used in tandem.It is also reversible. the opposite pads il! and sockets |43 being forthe purpose of properly oppositely applying the weights and scales undersuch circumstances. Thus it is particularly adaptable to a wide range o!cases where dynamometers are required. In any multiple of units theaction is smooth because of the large reduction in parasitic hydraulictorque which in the ordinary machine builds up vibrations. Suchvibrations in tandem units would become periodic and the present meansminimizes this contingency.

While the invention is disclosed in connection with a dynamometerapplication, it will be understood that it is also applicable to similarap-` paratus, such as slip couplings. brakes and the like.

In view of the above, it will be seen that the several objects o! theinvention are achieved and other advantageous results attained.

As many changes could be `made in the above constructions withoutdeparting from the scope of the invention, it is` intended that allmatter contained in the above description or show n in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

I claim:

l. Apparatus of the class described comprising inner and outerrelatively rotary members which are substantially radially spaced.flux-concentrating poles extending from one of the mem-- bers toward`theother and into close proximity with the latter, said poles beingperipherally spaced throughout an arc over only upper portions o! saidinner member, a eld coil in one of the members adapted to generate aflux held interlinklng the members through said poles, axial conduitmeans located between said members and having openings directed againstone o! the members for flooding it with a liquid coolant. means forintroducing coolant into said conduit means, the space between saidmembers being sumcient to accommodate beneath the inner member a re1-atively large pool of coolant without the rotor dripping therein. l

2. Apparatus of the class described comprising inner and outerrelatively rotary members which are substantially radially spaced.iiux-concentrating poles extending from one of the members toward theother and into close proximity with the latter, said poles beingperipherally spaced throughout an arc over only the upper portion ofsaid inner member, a ileld coil in one of the members adapted togenerate a nux neld inter-linking the members through said poles.conduit means located between said members and having openings directedagainst one of the members for oodlng` it with ,a liquid coolant, thatportion oi the conduit means which supplies most of the coolant beinglocated between said members throughout an arc under only lower portionsof the inner member. the space between said membere being suiiicient toaccommodate beneath the inner member and in the outer member arelatively large pool of coolant without the inner member dippingtherein.

3. A dynamometer comprising a rocking stator. an eddy-current rotortherein. said stator and with the latter to form 'ilux gaps, said polesbeing spaced throughout an arc over only upper portions oi' the rotor. afield coil in the stator lor generating a flux ileld interlinking thestator and the rotor through said poles, axially located conduit meansbetween the rotor and the stator having openings directed toward therotor for flooding it with a coolant, and means for introducing coolantinto said conduit means. the spacebetween the rotor and the statoradjacent the conduit means being of suilicient volume to accommodate arelatively large pool o! coolant.

4. A dynamorneter comprising a rocking stator, an eddy-current rotortherein, rotary liquid sealing meam between and near the ends of therotor and the stator, said stator and rotor being substantially radiallyspaced, axial flux-concentrating polar teeth extending from the statortoward the rotor and into close proximity with the iatter, said teethbeing peripherally spaced throughout an arc only over upper portions o!the rotor, a field coil in the stator for generating a flux heldinterlinking the stator and the rotor through said teeth, axiallylocated conduit means between the rotor and the stator having openingsdirected toward the rotor for flooding it with a coolant. means forintroducing coolant into said conduit means, the space between the rotorand the stator adjacent the conduitmeans being of suiticient volume toaccommodate a relatively large circulating pool of coolant without therotor dipping therein, and at least one axial conduit means over theupper arc of the rotor in the space between it and the stator andbetween said teeth which pipe is also open toward the rotor for pro-Jecting coolant thereon. the amount of cooling medium applied to therotor from said last-named conduit being substantially less than thevolume oi cooling medium applied below the rotor from said mst-namedconduit means.

5. A dynarnometer comprising a rocking stator. a rotor within the statorand having rotary liquid end seals with respect thereto, said rotor andsaid stator having relatively large radial spacing, axially extendingmagnetic pole means attached to the rotor and extending toward onlyupper arc portions oi the rotor, ileld means in the stator generating aiiux field interlinking the stator, the rotor and said axial poles,coolant pipes axially located in the space between the rotor and thestator, headers in the stator, said pipes having open ends communicatingwith said headers and having openings along their length directed towardthe rotor for amply flooding it with coolant, said pipes being locatedaround the lower arc of the rotor in radial space suillcient to form asubstantial pool of coolant withoutthe rotor dipping therein.

6. A dynamometer comprising a rocking stator. a rotor within the stator'and having rotary liquid end seals with respect thereto, said rotor andsaid stator having relatively large radial spacing, axially extendingmagnetic pole means attached to the stator and extending toward onlyupper arc portions of the rotor, annular field means in the statorgenerating a toric flux ileldccncentratingpclcsextendingtromtbestatortcinterlinking the stator. therotor and said axial poles, a plurality of coolant pipes axially locatedin the space between the'rotor and the stator. annular headers in therotor, said pipes having open ends communicating with said headers andhaving openings along Vtheir lengths directed toward the rotor forflooding it with coolant. the numberotplpesapplyingthegrsatcramountctcoolant being located under the lower arc of the rotor, the spacebetween said lower arc of the rotor and that of the stator beingsuflicient to carry a substantial pool .of coolant without the rotordipping therein.

7. A dynamometer comprising a composite rocking stator, said statorconsisting of an outer wall and a spaced internal wall, the latterhaving axial inwardly directed polar teeth and being provided with atleast one outwardly extending peripheral recess, an Iannular field coilin said recess, a rotor located within the stator and substantiallyspaced therefrom radially, said rotor having endwise portions extendingfrom the stator, endwise coolant seals between the stator and the rotor,annular coolant headers in the vends of the stator, and coolant pipesextending between .communications wi'th said headers and through thespace between the rotor .and stator.

8. A dynamometer comprising a composite rocking stator, said statorconsisting of an outer wall and a spaced internal wall, the latterhaving axial inwardly directed polar teeth and being provided withatleast one outwardly extending peripheral recess, an annular field coilin said recess, a rotor located within the stator and substantiallyspaced therefrom radially, said rotor having endwise portions extendingfrom the stator, endwise coolant seals between the stator and the rotor,annular coolant headers in the ends of the stator, and coolant pipesextending between communications with said headers and through the spacebetween the rotor and stator, said polar teeth extending into cio-seproximity to the rotor surface.

9. A dynamometer comprising a composite rocking stator, said statorconsisting of an outer wall and a spaced internal wall, the latterhaving axial inwardly directed polar teeth and being provided with atleast one outwardly extending peripheralV recess, an annular field coilin said recess, a rotor located within the stator and substantiallyspaced therefrom radially said rotor having endwise portions extendingfrom the stator, endwise coolant seals between the stator and the rotor,annular coolant headers in the ends of the stator, and coolant pipesextending between communications with said headers and through the spacebetween the rotor and stator, said polar teeth extending into closeproximity to the rotor surface, most of the pipes lying in a peripheralregion outside of that of the teeth and therebelow.

10. A dynamometer comprising a rocking stator having inwardly directedpolar teeth, a rotor within the stator and substantially spacedtherefrom radially, said teeth extending from the stator with their endsin close proximity to the rotor, said rotor having endwise portionsextending from the stator, coolant seals between the stator and therotor, liquid headers carried by the stator, coolant conduits extendingbetween communications with said headers and located in the spacebetweenvthe stator and the rotor and having coolant flooding openingsdirected toward the latter, the conduits which supply most of thecoolant lying in a peripheral region outside of that of said polar teethand therebelow, and a peripheral field coil supplying a toric flux fieldinterlinking the stator, rotor and polar teeth.

11. A dynamometer comprising a rocking stator having inwardly directedpolar teeth, a rotor within the stator and substantially spaced there-`from radially, said teeth extending from the sta- 10 tor with theirends in close proximity to the rotor, said rotor having endwise portionsextending from the stator, endwise coolant seals beytween the'stator andthe rotor, liquid headers carried at opposite ends of the rotor, coolantconduits extending between communications with said headers and located-inthe space between the stator and the rotor and having coolantiiooding openings directed toward the latter, the conduits supplyingmost of the coolant lying in a peripheral region outside of that of ingprovided with at least one outwardly extending peripheral recess, anannular field coil in said recess, a rotor located within the stator,said rotor having endwise portions extending from the stator, endwiseseals between the stator and the rotor, and flux-concentrating teethextending from the inner sleeve toward the rotor, the radial spacingbetween the rotor and said inner sleeve being substantial, axiallylocated pipes between the inner sleeve and the rotor having openings forimpinging coolant against the rotor, said stator having at least onehollow annular header with which said pipes communicate for receivingcoolant.

13. A dynamometer comprising a rocking stator, a rotor vlocated withinthe stator, said rotor having endwise portions extending from thestator, endwise seals between the stator and the rotor,flux-concentrating polar teeth extending from the inner sleeve towardthe rotor, an annular field coil providing a flux eld interlinking therotor, stator and polar teeth, the radial spacing between the rotor andsaid inner sleeve being substantial, axially located pipes between theinner sleeve and the rotor having openings for impinging coolant againstthe rotor, said stator having hollow annular endwise headers for coolantwith which said pipes communicate, flexible feed lines connected to`said headers respectively and extending above the stator in oppositedirections, each feed line receiving its coolant from a point at the endof the rotor which is opposite to the end at which the feed line isconnected to its respective header.

14. A dynamometer comprising a rocking stator having inwardly directedpolar teeth, a rotor within the stator and substantially spacedtherefrom radially, said teeth extending from the stator with their endsin close proximity to the rotor, said rotor having endwise portionsextending from the stator, endwise coolant seals between the stator andthe rotor, liquid headers carried at opposite ends of the rotor, aplurality of coolant pipes extending between communications with saidheaders and located in the space between the stator and the rotor andhaving coolant flooding openings directed toward the latter, the pipessupplying most of the coolant lying in a peripheral region outside ofthat of said polar teeth and therebelow, and a peripheral ileld coilsupplying a torio flux field interlinking the stator, rotor andpolarteeth.

15. A dynamoineter comprising bearing pedestals, a hollow stator mountedto rock in said pedestals, a rotor having bearings in the stator andhaving end portions extending therefrom, coolant-receiving means atopposite ends of said stator, separate flexible coolant supply pipes at-1 l tached to said coolant-receiving means vrespectively, coolant-supplyheaders mounted upon said pedestals, each ilexible coolant supply pipewhich is connected to one receiving means communieating with the headeron the pedestal which is at the opposite end of the stator.

16. A dynamometer comprising a stator, an annular field coil in thestator, a rotor within the stator passing through said coil, said statorand rotor being amply spaced radially, flux-concentrating teeth in theilux circuit oi' said coil and extending from the stator and into closeproximity to the rotor surface at upper arcuate portions of the latter,endwise coolant .headers in the stator, coolant pipes connecting saidheaders, said pipes having coolant openings adjacent the rotor and atits lower arcuate portions for projecting coolant against the rotor,said pipes being in the space between the rotor and the stator andconnecting said headers, and supports for the pipes at intervals along'the stator but bridging its bottom portion to allow for a sub'-stantial pool of coolant, said stator having bottom outlet means fromthe pool of coolant.

17. A dynamometercomprising a hollow cylindric stator, a cylindric rotortherein and-amphr spaced therefrom radially, annular coolant headers atthe ends o! the stator, coolant pipes connecting said headers and havingcoolant pro- Jection openings directed toward the stator, the number oi'pipes carrying the greatest coolant moan:

K volume being distributed adjacent the lower arc of therotor, andflux-concentrating poles projecting from the inside of the stator intoclose proximity with respect to the rotor over upper larcuate portionsthereof, and at least one annular field coil carried by the rotor andsupplying a ilux circuit through the rotor, poles and stator.

18. Apparatus of the class described comprising inner and outerrelatively rotary members vwhichA are substantially radially spaced,iiuxconcentrating poles extending from one oi the members toward theother and into close proximity with the latter, a field coil in one ofthe members .adapted to generate a iiux field interlinking the membersthrough said poles, said poles being peripherally spaced with a majorityof them located in a predetermined upper arc between the adjacentperipheries of the rotary members, thereby leaving in the remaining arcbetween said adjacent peripheries a space which is less obstructed bypoles than is the space in said upper arc, means for spraying coolantonto the inner rotary member primarily from said relatively unobstructedspace, said outer member having coolant outlet means from saidrelatively unobstructed space which -will let out coolant from the outermember, the arrangement being such that no pool of coolant in saidrelatively unobstructed space touches the rotor.

MARTIN P.

